Endometriosis occurs when endometrial tissue that is shed during menses is able to attach, invade and grow outside the uterus. Ectopic endometrial growth usually occurs within the pelvic region on the ovaries and other peritoneal organs, such as the bladder and colon, but it may also occur as far away as the lungs and brain. This condition is characterized by peritoneal inflammation, fibrosis, adhesions and ovarian cysts, which result in chronic pelvic pain, pain during intercourse (dyspareunia), painful periods (dysmenorrhea) and infertility. Still today, endometriosis remains a poorly understood condition that continues to incapacitate and affect the productivity and lifestyle of millions of women around the world. Stress is a significant component of many recurrent and chronic health problems, including endometriosis. Research studies have confirmed the negative effects of stress on many diseases. Circumstantial evidence suggest that a variety of stress management techniques including handling stressful situations and implementing lifestyle changes can help women suffering from endometriosis and other gynecological conditions. However it is not known whether stress affects the prevalence of endometriosis in women nor if stress can exacerbate its symptoms. This study will test the hypothesis that stress and changes in behavior under different types of stress can affect endometriosis progression in an established animal model of endometriosis. The specific aims of this proposal are to: 1) Determine if stress can exacerbate endometriosis;2) to determine whether the ability to control stress can decrease the extent of endometriosis;3) determine whether prior stress increases the likelihood of developing endometriosis;and 4) determine the role of mast cells in the development of endometriosis during stress. These studies will contribute to our understanding of the pathophysiological mechanisms of endometriosis under stressful conditions and to the possibility of implementing the management of stressful events in the life of endometriosis patients as a therapeutic approach.